Demonstrations of AIDS-associated malignancies and infections at FDG PET-CT

Biomarkers of Postpartum Depression: A Narrative Review

Postpartum depression (PPD) is a disorder that impairs the formation of the relationship between mother and child, and reduces the quality of life for affected women to a functionally significant degree. Studying markers associated with PPD can help in early detection, prevention, or monitoring treatment. The purpose of this paper is to review biomarkers linked to PPD and to present selected theories on the pathogenesis of the disease based on data from biomarker studies. The complex etiology of the disorder reduces the specificity and sensitivity of markers, but they remain a valuable source of information to help clinicians. The biggest challenge of the future will be to translate high-tech methods for detecting markers associated with postpartum depression into more readily available and less costly ones. Population-based studies are needed to test the utility of potential PPD markers.

Lymphomas of Central Nervous System

Central nervous system (CNS) lymphoma consists of primary central nervous system lymphoma (PCNSL) and secondary CNS involvement by systemic lymphoma. This chapter focuses on the former. PCNSL is a relative rare disease, accounting for approximately 2.4-4.9% of all primary CNS tumors. It is an extra-nodal variant of non-Hodgkin's lymphoma (NHL), confined to the brain, leptomeninges, spinal cord, and eyes, with no systemic involvement. Recently, elderly patients (≥ 60 years) are increasing. Histologically, B cell blasts, which originate from late germinal center exit B cell, are growing and homing in CNS. Immunohistochemically, these cells are positive for PAX5, CD19, CD20, CD22, and CD79a. PCNSL shows relatively characteristic appearances on CT, MR imaging, and PET. Treatment first line of PCNSL is HD-MTX-based chemotherapy with or without rituximab and irradiation. Severe side-effect of this treatment is delayed onset neurotoxicity, which cause of cognitive impairment. Therefore, combined chemotherapy alone or chemotherapy with reduced-dose irradiation is more recommended for elderly patients. There is no established standard care for relapse of the PCNSLs. Temsirolimus, lenalidomide, temozolomide, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib are candidates for refractory patients. The prognosis of PCNSL has significantly improved over the last decades (median OS: 26 months, 5-year survival: 31%). Younger than 60 age and WHO performance status less than < or = 1 are associated with a significantly better overall survival.

Clinical features and 18F-FDG PET/CT for distinguishing of malignant lymphoma from inflammatory lymphadenopathy in HIV-infected patients

Background

It is vital to distinguish between inflammatory and malignant lymphadenopathy in human immunodeficiency virus (HIV) infected individuals. The purpose of our study was to differentiate the variations in the clinical characteristics of HIV patients, and apply ¹⁸F-FDG PET/CT parameters for distinguishing of malignant lymphoma and inflammatory lymphadenopathy in such patients.

Methods

This retrospective cross-sectional study included 59 consecutive HIV-infected patients who underwent whole-body ¹⁸F-FDG PET/CT. Of these patients, 37 had biopsy-proven HIV-associated lymphoma, and 22 with HIV-associated inflammatory lymphadenopathy were used as controls. The determined parameters were the maximum of standard uptake value (SUV_max), SUV_max of only lymph nodes (SUV_LN), the most FDG-avid lesion-to-liver SUV_max ratio (SUR_max), laboratory examinations and demographics. The optimal cut-off of ¹⁸F-FDG PET/CT value was analyzed by receiver operating characteristic curve (ROC).

Results

Considering the clinical records, the Karnofsky Performance Status (KPS) scores in patients with inflammatory lymphadenopathy were obviously higher than those in patients with malignant lymphoma (P = 0.015), whereas lymphocyte counts and lactate dehydrogenase (LDH) were obviously lower (P = 0.014 and 0.010, respectively). For the ¹⁸F-FDG PET/CT imaging, extra-lymphatic lesions, especially digestive tract and Waldeyer’s ring, occurred more frequently in malignant lymphoma than inflammatory lymphadenopathy. Furthermore, the SUR_max and SUV_LN in malignant lymphoma were markedly higher than those in inflammatory lymphadenopathy (P = 0.000 and 0.000, respectively). The cut-off point of 3.1 for SUR_max had higher specificity (91.9%) and relatively reasonable sensitivity (68.2%) and the cut-off point of 8.0 for the SUV_LN had high specificity (89.2%) and relatively reasonable sensitivity (63.6%).

Conclusion

Our study identified the distinctive characteristics of the clinical manifestations, the SUR_max, SUV_LN and detectability of extra-lymphatic lesions on ¹⁸F-FDG PET, and thus provides a new basis for distinguishing of malignant lymphoma from inflammatory lymphadenopathy in HIV-infected patients.

Imaging of Kaposi sarcoma

Kaposi sarcoma (KS) is a form of cancer that primarily appears on the skin but can potentially involve internal organs. There are several types of KS. The purpose of this article is to discuss the manifestations of KS and their appearance on imaging, the differential diagnoses associated with these findings, and molecular markers associated with KS that can aid appropriate diagnosis and therapy.

ACR Appropriateness Criteria® Acute Respiratory Illness in Immunocompromised Patients

The immunocompromised patient with an acute respiratory illness (ARI) may present with fever, chills, weight loss, cough, shortness of breath, or chest pain. The number of immunocompromised patients continues to rise with medical advances including solid organ and stem cell transplantation, chemotherapy, and immunomodulatory therapy, along with the continued presence of human immunodeficiency virus and acquired immunodeficiency syndrome. Given the myriad of pathogens that can infect immunocompromised individuals, identifying the specific organism or organisms causing the lung disease can be elusive. Moreover, immunocompromised patients often receive prophylactic or empiric antimicrobial therapy, further complicating diagnostic evaluation. Noninfectious causes for ARI should also be considered, including pulmonary edema, drug-induced lung disease, atelectasis, malignancy, radiation-induced lung disease, pulmonary hemorrhage, diffuse alveolar damage, organizing pneumonia, lung transplant rejection, and pulmonary thromboembolic disease. As many immunocompromised patients with ARI progress along a rapid and potentially fatal course, timely selection of appropriate imaging is of great importance in this setting. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking, or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Computed tomography textural analysis for the differentiation of chronic lymphocytic leukemia and diffuse large B cell lymphoma of Richter syndrome

OBJECTIVE

To test the hypothesis that both indolent and aggressive chronic lymphocytic leukemia (CLL) can be differentiated from diffuse large B cell lymphoma (DLBCL) of Richter syndrome (RS) by CT texture analysis (CTTA) of involved lymph nodes.

MATERIAL AND METHODS

We retrospectively included 52 patients with indolent CLL (26/52), aggressive CLL (8/52), and DLBCL of RS (18/52), who underwent standardized contrast-enhanced CT. In main lymphoma tissue, VOIs were generated from which CTTA features including first-, second-, and higher-order textural features were extracted. CTTA features were compared between the entire CLL group, the indolent CLL subtype, the aggressive CLL subtype, and DLBCL using a Kruskal-Wallis test. All p values were adjusted after the Bonferroni correction. ROC analyses for significant CTTA features were performed to determine cut-off values for differentiation between the groups.

RESULTS

Compared with DLBCL of RS, CTTA of the entire CLL group showed significant differences of entropy heterogeneity (p < 0.001), mean intensity (p < 0.001), mean average (p = 0.02), and number non-uniformity gray-level dependence matrix (NGLDM) (p = 0.03). Indolent CLL significantly differed for entropy (p < 0.001), uniformity of heterogeneity (p = 0.02), mean intensity (p < 0.001), and mean average (p = 0.01). Aggressive CLL showed significant differences in mean intensity (p = 0.04). For differentiation between CLL and DLBCL of RS, cut-off values for mean intensity and entropy of heterogeneity were defined (e.g., 6.63 for entropy heterogeneity [aggressive CLL vs. DLBCL]; sensitivity 0.78; specificity 0.63).

CONCLUSIONS

CTTA features of ultrastructure and vascularization significantly differ in CLL compared with that in DLBCL of Richter syndrome, allowing complementary to visual features for noninvasive differentiation by contrast-enhanced CT.

KEY POINTS

• Richter transformation of CLL into DLBCL results in structural changes in lymph node architecture and vascularization that can be detected by CTTA. • First-order CT textural features including intensity and heterogeneity significantly differ between both indolent CLL and aggressive CLL and DLBCL of Richter syndrome. • CT texture analysis allows for noninvasive detection of Richter syndrome which is of prognostic value.

Approach to Peribronchovascular Disease on CT

Diseases that are predominantly peribronchovascular in distribution on computed tomography by definition involve the bronchi, adjacent vasculature, and associated lymphatics involving the central or axial lung interstitium. An understanding of diseases that can present with focal peribronchovascular findings is useful for establishing diagnoses and guiding patient management. This review will cover clinical and imaging features that may assist in differentiating amongst the various causes of primarily peribronchovascular disease.

Fever of unknown origin in cancer patients

Fever of unknown origin (FUO) remains a challenging clinical problem, namely in patients with cancer. In cancer patients, FUO may be due to the cancer itself, as it is the case of hematological malignancies; digestive tumors (colon cancer, liver metastases) are significantly associated with FUO and infection can be demonstrated in some cases. Prevention with G-CSF and empirical antimicrobial therapy are essential approaches for the management of FUO in cancer patients. New diagnostic approaches, such as PET imaging, should be further evaluated in cancer patients with FUO.

Growing applications of FDG PET-CT imaging in non-oncologic conditions

As the number of clinical applications of 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET-CT) grows, familiarity with the conditions that can be diagnosed by this modality and when relevant pieces of additional information can be obtained becomes increasingly important for both requesting physicians and nuclear medicine physicians or radiologists who interpret the findings. Apart from its heavy use in clinical oncology, FDG PET-CT is widely used in a variety of non-oncologic conditions interconnecting to such disciplines as general internal medicine, infectious diseases, cardiology, neurology, surgery, traumatology, orthopedics, pediatrics, endocrinology, rheumatology, psychiatry, neuropsychology, and cognitive neuroscience. The aim of this review was to summarize the current evidence of FDG PET-CT applications in evaluating non-oncologic pathologies and the relevant information it can add to achieve a final diagnosis.

FDG-PET imaging in HIV infection and tuberculosis

The intersection and syndemic interaction between the human immunodeficiency virus (HIV) and tuberculosis (TB) epidemics have global prevalence with devastating morbidity and massive mortality. Using FDG-PET imaging it was shown that in HIV-infected individuals, involvement of the head and neck precedes that of the chest and of the abdomen. The sequence of lymph node involvement observed suggests the existence of a diffusible activation mediator that may be targeted via therapeutic intervention strategies. Furthermore, the degree of FDG uptake proved directly related to viral load and inversely related to CD4 cell count. Available data in acquired immune deficiency syndrome (AIDS)-defining cancers further suggest that FDG-PET/CT imaging may be useful for prognostication of cervical cancer and for identifying appropriate sites for biopsy, staging, and monitoring lymphoproliferative activity owing to HIV-associated Kaposi sarcoma and multicentric Castleman disease. Inversely, in HIV-associated lymphoma, FDG uptake in HIV-involved lymphoid tissue was shown to reduce the specificity of FDG-PET imaging findings, the effect of which in clinical practice warrants further investigation. In the latter setting, knowledge of viremia appears to be essential for FDG-PET image interpretation. Early HIV-associated neurocognitive disorder, formerly known as AIDS dementia complex, proved to be characterized by striatal hypermetabolism and progressive HIV-associated neurocognitive disorder or AIDS dementia complex by a decrease in subcortical and cortical metabolism. In lipodystrophic HIV-infected individuals, lipodystrophy proved associated with increased glucose uptake by adipose tissue, likely resulting from the metabolic stress of adipose tissue in response to highly active antiretroviral therapy. Furthermore, ongoing chronic low-grade infection in arteries of HIV-infected individuals could be depicted by FDG-PET/CT imaging. And there is promising data that FDG-PET/CT in HIV may serve as a new marker for the evaluation of thymic function in HIV-infected patients. In the setting of TB, FDG-PET has proven unable to differentiate malignancy from TB in patients presenting with solitary pulmonary nodules, including those suffering from HIV, and thus cannot be used as a tool to reduce futile biopsy or thoracotomy in these patients. In patients presenting with extrapulmonary TB, FDG-PET imaging was found to be significantly more efficient when compared with CT for the identification of more sites of involvement. Thus supporting that FDG-PET/CT can demonstrate lesion extent, serve as guide for biopsy with aspiration for culture, assist surgery planning and contribute to follow-up. Limited available data suggest that quantitative FDG-PET findings may allow for prediction or rapid assessment, at 4 months following treatment instigation, of response to antituberculostatics in TB-infected HIV patients. These results and more recent findings suggest a role for FDG-PET/CT imaging in the evaluation of therapeutic response in TB patients.

Differentiation of HIV-associated lymphoma from HIV-associated reactive adenopathy using quantitative FDG PET and symmetry

PURPOSE

To determine the diagnostic accuracy of a semiautomated (18)F-FDG PET/CT measurement of total lesion glycolysis (TLG), maximum and peak standardized uptake value at lean body mass (SUL-Max and SUL-Peak), qualitative estimates of left/right nodal symmetry and FDG uptake for differentiating lymphoma from reactive adenopathy in HIV-infected patients.

METHODS

We retrospectively analyzed 41 whole-body (18)F-FDG PET/CT studies performed in HIV-infected patients for clinical reasons. The study received institutional review board approval. Of the 41 patients, 19 had biopsy-proven untreated lymphoma, and 22 with reactive adenopathy without malignancy on follow-up were used as controls. Nodal and extranodal visual qualitative metabolic scores, SUL-Max, SUL-Peak, CT nodal size, and PERCIST 1.0 threshold-based TLG and metabolic tumor volume (MTV) were determined. The qualitative intensity of nodal involvement and symmetry of uptake were compared using receiver operator curve (ROC) analysis. HIV plasma viral RNA measurements were also obtained.

RESULTS

All of the quantitative PET metrics performed well in differentiating lymphoma from reactive adenopathy and performed better than qualitative visual intensity scores. The areas under the ROC curves (AUC) were significantly higher for TLG = 0.96, single SUL-Peak = 0.96, single SUL-Max = 0.97, and MTV = 0.96, compared to 0.67 for CT nodal size (p < 0.001). These PET metrics performed best in separating the two populations in aviremic patients, with AUCs of 1 (AUC 0.91 for CT nodal size). TLG, MTV, SUL-Peak and SUL-Max were more reliable markers among viremic individuals, with AUCs between 0.84 and 0.93, compared to other metrics. PET metrics were significantly correlated with plasma viral load in HIV-reactive adenopathy controls. Asymmetrical FDG uptake had an accuracy of 90.4 % for differentiating lymphoma from reactive adenopathy in HIV-infected patients.

CONCLUSION

Quantitative PET metabolic metrics as well as the qualitative assessment of symmetry of nodal uptake appear to be valuable tools for differentiating lymphoma from reactive adenopathy in HIV-infected patients using FDG PET. These parameters appear more robust in aviremic patients.